A number of collaborative efforts involve investigation of the characteristics of unusual or less debilitating (e.g., headache) neurologic disease phenomena. Unusual associations or space/time clusters of neurologic disorders may provide leads to etiology or therapy. These may be tested through more formal approaches. A study of over 100 cases of pseudotumor cerebri has been completed. This study documented an inverse linear relationship between cerebrospinal fluid (CSF) opening pressure and CSF protein content. Further analysis of these data are in progress. Descriptive and analytic studies of spastic paraparesis are being conducted in Columbia, India, the Seychelles Islands, and the West Indies. A retrospective cohort approach is being used to investigate the sequelae of cerebral malaria due to infection with Plasmodium Falciparum. Surveys for Parkinson's disease are being conducted in former Far East prisoners of war.